Move setmode and getmode declarations to <bsd/unistd.h>

This is were they are located on the BSDs.

include/bsd/stdlib.h

@@ -37,6 +37,9 @@
 /* For compatibility with NetBSD, which defines humanize_number here. */
 #include <libutil.h>
 
+/* FIXME: Temporary inclusion to avoid API breakage, will be removed soon. */
+#include <bsd/unistd.h>
+
 __BEGIN_DECLS
 u_int32_t arc4random();
 void arc4random_stir();
@@ -51,13 +54,6 @@ void setprogname (char *);
 
 int heapsort (void *, size_t, size_t, int (*)(const void *, const void *));
 
-#ifndef S_ISTXT
-#define S_ISTXT S_ISVTX
-#endif
-
-mode_t getmode(const void *set, mode_t mode);
-void *setmode(const char *mode_str);
-
 long long strtonum(const char *nptr, long long minval, long long maxval,
                    const char **errstr);
 __END_DECLS